Let us make an in-depth study of the important signs and symptoms of parasitic diseases which are discussed hereunder:
Abscess, Amoebic:
The liver is tender and enlarged. There is intense pain, fever, with night sweats when abscess in formed.
Abscess, Filarial:
Along the lymphatic’s, filarial abscess may appear and the segments of the adult worms may be seen in the abscess drainage which is free from bacteria.
Anemia:
In malaria, ankylostomiasis, diphyllobothriasis, anaemia is common. Microcytic hypochromic anemia is common in ankylostomiasis, malaria, because of blood loss. In case of hookworm infection, dietary intake of iron may prevent anemia. A macrocytic anemia may develop in diphyllobothriasis, because of vitamin B12 deprivation by the worm attached to the jejunal wall.
The proliferation of infected reticuloendothelial cells in the bone marrow is responsible for anemia in Kala-azar, and Chagas’ disease. In trypanosomiasis, schistosomiasis, fasciolopsiasis, systemic toxicity and nutritional defects may result in anemia.
Appendicitis:
The blockage of the lumen of the appendix by Ascaris and Trichuris causes appendicitis. In amoebiasis, acute appendicitis may occur.
Ascites:
Tissue proliferation around the eggs leading to fibrosis of the liver may cause ascites in Schistosoma mansoni and S. japonicum.
Asthma, Bronchial:
Migration of larva of Ascaris lumbricoides through the lungs may cause bronchial asthma.
Calabar Swellings:
In loissis, subcutaneous swellings are observed. They are painful and pruritic.
Chagoma:
A hard, reddened, raised, primary lesion develops on the face, neck, abdomen or limbs in Chagas’ disease.
Chorioretinitis:
Toxoplasma may infect the retina and choroid and there will be disturbance in eye sight.
Chyluria:
Lymphatic fluid is passed in the urine which is milky white and contains microfilariae of Wuchereria bancrofti.
Coma:
It is observed in falciparum malaria and in African trypanosomiasis.
Conjunctivitis:
Onchocercal infection produces chronic conjunctivitis.
Convulsions:
These may be seen in the malarial paroxysm and in Ascaris infection in children.
Dermatitis:
Strongyloides larvae, hookworm larvae and schistosoma cercariae penetrate through the skin and cause a localised edema and pruritus leading to dermatitis. The cutaneous larva migrans reaction caused by larvae of Ankylostoma braziliense is indicated by a red papule at the site of entry and there will be severe itching.
Adult Loa loa beneath the skin may cause dermatitis. The adult female Dracunculus medinensis beneath the skin produces blister. Microfilariae of Onchocerca volvulus in the skin may cause pruritic. Sarcoptes scabei under the skin causes lesions similar to those of cutaneous larva migrans.
Diarrhea:
Infiltration of the intestinal sub-mucosa by macrophages containing Leishmani donovania may cause the mucosal ulceration and diarrhoea in Kala azar. Mucosal capillaries of the intestine plugged with parasitized red blood cells cause profuse watery diarrhoea in falciparum malaria. Mucosal ulceration in amoebiasis or balantidiasis may produce diarrhoea.
A mild mucoid diarrhoea caused by Giardiasis may lead to malabsorption of fat steatorrhoea’ (diarrhoea with fat). Mucous diarrhoea may be caused by the development of cysticercoids of Hymenolepis nana within the intestinal villi. Mild diarrhoea followed by constipation or severe diarrhoea may be observed in strongyloides infection.
Diarrhoea of toxic origin, characterised by nausea, vomiting, hepatic tenderness and fever is caused by Schistosoma mansoni and S. japonicum infections. Egg deposition in the intestinal wall may be responsible for profuse diarrhoea or dysentery in Schistosomiasis.
Nausea, vomiting and diarrhoea are indicated in heavy hookworm and whipworm infections. In fasciolopsiasis, diarrhoea with much undigested food is observed. Sometimes, there may be diarrhoea in taeniasis and diphyllobothriasis.
Dysentery:
The passage of six to eight more mucoid blood flecked stools per day is characteristic of acute amebic dysentery.There may be abdominal pain and tenderness.
Elephantiasis:
Filarial elephantiasis is a chronic enlargement of the limb, scrotum, breast or vulva with hyperplasia of the connective tissue and skin. Rarely, the blockage of the lymphatic drainage due to fibrosis caused by eggs deposited by Schistosoma haematobium in vesicle plexus of veins.
Eosinophilia:
In many helminthic infections, eosinophilia is common. Tissue parasites provoke a higher eosinophilia than the intestinal parasites. It is not characteristic in protozoan infections.
Epididymitis:
It is seen in filarial infection.
Funiculitis:
Inflammation of the spermatic cord occurs as an early symptom of filariasis.
Hematuria:
There may be terminal hematuria in the last few drops of urine in Schistosoma hematobium infection.
Hydrocele:
It is common in filariasis.
Hydrocephalus:
In congenital toxoplasmosis, hydrocephalus or microcephaly is common.
Hyperpigmentation:
Hyperpigmentation of the skin over the cheeks, temples and around the mouth is seen in Kala azar. In onchocercosis, allergic dermatitis may result in hyperpigmentation of the area on the face, neck or ears.
Jaundice:
In severe liver fluke infection, obstructive jaundice may be observed. In falciparum malaria, there is marked enlargement and tenderness of the liver, with jaundice appearing on second day.
Leucocytosis:
It is very common only in amebic abscess. Leucocytosis, followed by leucopenia, is common in many protozoan and helminthic infections.
Leucopenia:
It is generally seen in Kala-azar.
Lymphadenitis:
It is common in filariasis. Axillary and inguinal lymph nodes are enlarged, painful and tender. In acute stage of Chagas’ disease, there is a generalized lymphadenopathy.
Lymphangitis:
Acute lymphangitis is an early symptom of filariasis. It is followed by fever. When it occurs on a limb, it progresses distally.
Lymphocytosis:
It is generally seen in Chagas’ disease.
Lymph Varices:
Due to lymphatic blockage in filariasis, the lymphatic vessels of the inguinal and femoral areas are dilated. The soft lobulated swellings may rupture and drain.
Meningoencephalitis:
In African sleeping sickness, the symptoms of meningoencephalitis may result due to the invasion of the central nervous system by trypanosomes. There may be confusion, headache, drowsiness and, finally, coma. In Chagas’ disease, the symptoms are similar but milder. Meningoencephalitis is also observed in falciparum malaria.
Microcehphalus:
See Hydrocephalus.
Monocytosis:
In both protozoal and helminthic infection, monocytosis is a frequent finding.
Monocardit:
It is characteristic of Chagas’ disease and trichinosis. In trichinosis, the migration of the larvae through the myocardium causes myocarditis. It is also seen in toxoplasmosis, as a result of invasion of toxoplasma in the myocardium.
Myositis:
Migration of Trichinella spiralis larva in the muscles causes myositis.
Neurological Symptoms:
See under Meningoencephalitis.
Nodules, Subcutaneous.
Onchocercomas, cysticercus larva of Taenia solium and Echinococcus cysts may be found in the subcutaneous tissues forming nodules of 0.5 to 3.0 centimetre in diameter.
Obstruction, Intestinal:
Ascaris may cause complete intestinal obstruction in children with abdominal pain, vomiting, distension and hyper peristalsis.
Ocular Symptoms:
See Conjunctivitis.
Edema:
Migrating larvae of Trichinella spiralis may cause vasculitis leading to edema. The migration of adult Loa loa across the eyeball or lid may cause unilateral edema with local pruritis and intense pain. Calabar swellings are also seen in loiasis; while in onchocerciasis, there will be edema of face, neck, ears followed by an intense pruritus and erythema. The most common type is unilateral edema of eyelids (Romana’s sign). Edema of the face and legs is seen in severe hookworm infection, fasciolopsis and diphyllobothriasis.
Onchocercoma:
Adult worms of Onchocerca volvulus remain coiled underneath the skin, enclosed in a fibrous tissue capsule.
Orchitis:
Recurrent attacks of hydrocele may cause orchitis in filariasis.
Pain:
Abdominal pain is said to accompany many of the intestinal parasitic infections. Severe pain may indicate intestinal obstruction, perforation and peritonitis or bile duct blockage in ascariasis.
Peritonitis:
Penetration of Ascaris through the wall of the intestine leads to peritonitis, with pain, abdominal distension and tenderness. Ulcers in severe amoebic dysentery may erode through the wall of the intestine to initiate peritonitis.
Pneumonitis:
When the larvae of Ascaris lumbricoides breakout of the capillaries into the alveoli cause pneumonitis. In the neonatal period, acute toxoplasmosis causes pneumonitis.
Proteinuria:
Proteinuria with hyaline and granular casts in the urine is common in falciparum malaria.
Pruritus Ani:
It accompanies pinworm infection. Sometimes, it may also be associated with migration of gravid proglottids of Taenia saginata out of anus.
Pulmonary Symptoms, Chronic:
Pseudo- tubercle formation in lungs around ova, of Schistosoma, which are carried to lungs. Chronic cough is characteristic of Paragonimiasis. Cough is the primary symptom in pulmonary echinococcosis.
Rash:
In early stage of schistosome infection and in ascariasis, an allergic urticarial rash may appear. In the course of trichina infection, a macular or maculopapular eruption may be seen.
Romana’s Sign:
In early stage of Trypanosoma cruzi infection (Chagas’ disease), unilateral edema involving both the eyelids may appear.
Splenomegaly:
In both African and American sleeping sickness, splenomegaly may be noticed. The spleen is said to enlarge downwards about an inch per month in Kala-azar. The spleen enlarges and becomes tender during an acute attack of malaria. Hepatic fibrosis caused by the egg deposited by Schistosoma mansoni and S. japonicum in the liver may result into splenomegaly.
Tachycardia:
It could be observed in African and American sleeping sickness, which is characterised by a fast pulse.
Ulcers, Cutaneous:
Oriental sore or Delhi boil, caused by Leishmania tropica, is characterised by a shallow ulcer. L.braziliens is also produces cutaneous ulcerations which involve the nasal mucosa, the soft and hard palate, nasal septum, pharynx and larynx. Dracunculus medinensis initially produces blister which transforms into ulcer. Adult worm can be seen in the centre of the ulcer.
Urethritis:
Trichomonas vaginalis causes ‘non-specific urethritis’.
Vaginitis:
In Trichomonas vaginalis infection, vagina is congested and there will be yellowish discharge.